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Experimental study on soil moisture lower limit-based drip irrigation schedule for Lycium barbarum in Ningxia arid area |
XU Ligang*, WANG Huaibo, BAO Ziyun, LI Jinze |
Ningxia Institute of Water Resources Research, Yinchuan, Ningxia 750021, China |
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Abstract Considering Ningqi No.7 Lycium barbarum as study object, field experiments were carried out in Tongxin county of Ningxia during 2016—2017. In the experiments, there were four critical control irrigation stages and three control irrigation levels, resulting in eight treatments totally. The root soil moisture, leaf photosynthetic physiological indexes, yield and quality of Lycium barbarum were investigated in different growth stages and lower limits of soil moisture. The water consumption and water use efficiency were analyzed and a drip irrigation schedule for Lycium barbarum in Ningxia arid area was proposed based on the lower limits of soil moisture. The results showed that the soil moisture in the 20-60 cm soil layer was the highest in the root area of Lycium barbarum in different treatments. The leaf stomatal conductance was increased with increasing lower limit of soil moisture, and the higher the soil moisture lower limit and the bigger the transpiration rate, but the leaf water use efficiency was opposite. The water consumption rose with increasing lower limit of soil moisture in the growth stage in 2016—2017, and their increase rates were 10.8% and 12.8%, respectively. The average water consumption was 386.6-463.2 mm and it was the largest in summer fruiting period with statistics significance, therefore, this is the critical stage. The maximum yields were 2 208.15 kg/hm2 and 2 571.30 kg/hm2 in 2016—2017, respectively, and the water use efficiency was the highest at 0.39 kg/m3. The influence of soil moisture on quality of Lycium barbarum is not statistically significant. The content of glutinous polysaccharide was relatively high in lower moisture treatment. The whole growth stage was divided into six irrigation stages, among which the irrigation quota in sprout stage was 375 m3/hm2(spring water). The lower limit of soil moisture is 50%θf(θf is field moisture capacity)in spring growth stage, 65%θf in flowering stage, 65%θf in summer fruiting stage, 55%θf in autumn fruiting stage, and the upper limit was 95%θf. The irrigation quota was 450 m3/hm2 during winter dormancy. Those outcomes will provide a technical support for scientific irrigation and planting management of Lycium barbarum in arid areas.
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Received: 11 August 2018
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